NEW RODS MOVE BEFORE DIFFERENTIATING IN ADULT TELEOST RETINA

To understand the cellular context of neuronal differentiation in the vertebrate retina, we analyzed the behavior of a class of progenitor c ells in the outer nuclear layer of the teleost retina which divide thr oughout the animal's life and generate only rod photoreceptors. We pre sent evidence that these progenitors reside adjacent to the outer limi ting membrane of the retina during all phases of cell cycle. After fin al cell division, postmitotic cells move inward, toward the vitreal bo undary of the outer nuclear layer, before they give rise to new rods. This movement is remarkable because it occurs in the mature, functioni ng retina. We hypothesize that only one of the two progenitor daughter cells moves while the other remains adjacent to the outer limiting me mbrane to divide again. (C) 1995 Academic Press, Inc.